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Evolution of carnivory as a response to nutrient poor environments

Joined
Feb 16, 2015
Messages
171
Location
Nalasopara (near Bombay/Mumbai)
This is repeated everywhere. But it doesn't make sense to me. Or, for that matter the alleged inability of CPs to deal with high TDS. fertilizers, etc. I've started fertilizing recently, and am seeing no harm, but before I decided to try fertilizing, I gave it much thought. CP's don't grow in a vacuum. There are plants all around them in the allegedly "nutrient poor" environment doing just fine. I won't comment on bogs, since I've never seen one. But there are other bog plants too and there are enough CPs that don't live in bogs. There is soil everywhere else!

I saw photos of butterworts in some meadow and there were a COW in the background. A cow deposits *cough* farm manure.

Orchids grow in similar places as nepenthes. Heck the nepenthes and orchids thrive on TREES! There is enough nutrition in the soil to grow entire trees for the nepenthes to climb. And the surrounding vegetation, etc. If carnivorous plants were to die every time a dog or wolf or whatever decided to piddle on them, they wouldn't have survived (that would also be not just um... high TDS but urea....)

My nepenthes are doing just fine. In fact, fertilizing has helped intermediates and highlanders do better in my hot climate than they were doing before I fertilized them. They also put on size faster, which also ties in to the observations about the plants in forests, etc. We don't know a lot about how fast nepenthes reach maturity in forests. If the plants in forests grew as slowly as those we have and were as vulnerable to damp off and what not... they would be extinct. Think, even of the notorious slow growers. The infamous villosa. If vilosa in the forest reached a sum total of a few inches over years..... but the forest floor has a lot more nutrition than our pots.

I'm playing it safe by watering often between fertilizing, but so far I haven't killed anything from fertilizing as long as I stay away from anything in trays. I don't exactly focus on the drosera, but there are drosera volunteering in nepenthes pots too and they are alive.

I'm wondering how much of what we believe is truth and how much is plain CP superstition.

Anyone know better?
 
Joined
Oct 17, 2016
Messages
114
Location
Seattle, WA USA
Carnivory is one way but clearly not the only way to adapt. The added nitrogen and trace elements give them an extra edge and help them produce more seed but with certain exceptions, most carnivorous plants can survive without prey. They just do better with it. Other plants, like bog orchids, bog violets, cranberries and many more, also live in such soils without carnivory.

You might already know this but it’s worth saying also: Evolution doesn’t happen as a “response to” a condition; that is, a condition doesn’t cause plants to evolve something in response. It’s selection of traits that give a certain population an advantage. It seems to be nit picky but it’s important: The reason that we don’t generally find carnivorous plants in rich soil habitats is not because they didn’t receive a stimulus to develop it. It’s because even if a proto-carnivorous trait developed, it did not provide enough of an advantage to the plant to cause that trait to be passed on in increased numbers of offspring. An example is teasel with its wells at each leaf node. It makes it harder for insects to crawl up and reach the flowers and developing seeds. Insects do sometimes fall in and drown, and if the plant inhabited nutrient-poor soils, one might expect a plant that could extract nutrients from those dead insects to have a distinct advantage. Who knows, maybe certain plants with that trait have existed. But teasel grows in normal soils, with ample nutrients, so the bit of nitrogen that a few dead bugs might provide is nothing compared with what the plant gets through its roots. Result: There’s no advantage that would cause that plant to out-compete other teasel plants, produce more seed, and cause that trait to become fixed in the population . Now if teasel had already adapted to acid soils, and plants that had insects dying in their leaves benefited and produced more seed, then perhaps plants with slippery leaves might also get selected for, and then plants that were more attractive to insects because of nectaries, or a particular smell or color...you see where I’m going here.

Some, but not all, plants normally found in normal soils that can survive in acid, nutrient-poor soils under certain circumstances, but the bigger issue is, can they compete with the plants that are better adapted to those conditions? They can’t, and this is why acid bog environments have specific plant communities (not necessarily carnivorous) that thrive in them. I had seeds of evening primrose that got scattered into some sundew pots and I had been carefully picking out the seedlings. But others came up after them, so I just let them be. 4 months later, they still hardly have a normal leaf on them, while in normal soil they would be huge now.

But these are fragile environments, and when something happens to change the soil chemistry, like changing water table that kills off the Sphagnum, or nutrient runoff from lawns (as is happening around the Queen Bog near Lake Sammamish east of Seattle), those plants suddenly can move in, and can quickly turn a peat bog into a more alkaline marsh. I lived by a former bog in Shoreline (a suburb of Seattle) and while the soil is still peat-based, the lawn fertilizer runoff as well as septic tank leaching and God knows what else, has made it nearly impossible for Sphagnum to grow there, much less compete. It’s taken over by Himalayan Blackberry, Cattail, Yellow Flag Iris and Spirea, to name a few. So it’s not only outright draining and grading of/construction on bogs that threaten the plants we love, it’s the simple act of garden fertilizing and building septic systems that has disastrous effects on them.




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